1. Field of the Invention
This invention relates to apparatus for positioning an opening of a sack which is disposed at the leading end of a series of shingled sacks that have been unwound from a roll of shingled sacks. More particularly, the invention relates to apparatus for aligning the leading edge of a sack relative to a longitudinal conveying direction, and also for positioning side edges of the sack relative to a center line that extends in the conveying direction.
2. Description of the Prior Art
Published German Application No. 28 04 178 discloses an apparatus that serves to transfer to a filling device the leading sack of a series of shingled sacks which have been unwound from a roll of such sacks. The known apparatus does not perform an orientation of the sack so each sack that is to be filled is aligned with gripping arms of a sack transfer apparatus for transferring the sack to the filling device.
The individual sacks which are to be separated from a series of shingled sacks can easily slip relative to the other sacks so that a conveyor belt is not sufficient to convey each sack as reliably as is required to a properly aligned position, in which the sack can satisfactorily be taken over by the gripping means of the sack transfer apparatus. Additionally, the sacks can possibly be delivered in a laterally offset position and may differ in width owing to inevitable manufacturing tolerances. The gripping means cannot satisfactorily transfer the sacks unless the sacks are centered, even if they differ in width.
Apparatus for aligning sheets of sections of tubular films are disclosed in published German Applications Nos. 11 80 378 and 21 44 950.